RSIC COMPUTER CODE PSR-096

1. NAME AND TITLE

1DX: A One-Dimensional Diffusion Code System for Producing Energy Group Collapsed and Self-Shielded Cross Sections.

AUXILIARY ROUTINE

ICLOCK: Optional Specialized Subroutine.

2. CONTRIBUTORS

Battelle Pacific Northwest Laboratory, Richland, Washington (A).

Argonne National Laboratory, Argonne, Illinois (B).

3. CODING LANGUAGE AND COMPUTER

Fortran IV and Assembler Language; IBM 360/370, UNIVAC 1108.

4. NATURE OF PROBLEM SOLVED

1DX is a multipurpose, one-dimensional diffusion code for generating cross sections to be used in fast reactor analyses. It is designed to 1) compute and punch resonance shielded cross sections using data in the "Russian" format, 2) compute and punch group-collapsed microscopic and/or macroscopic cross sections averaged over the spectrum in any specified zone, and 3) compute k_eff and perform criticality searches on time absorption, material concentrations, zone dimensions, and buckling using either a flux or an adjoint model.

5. NATURE OF PROBLEM SOLVED

1DX calculates resonance shielded cross sections using data (infinite dilution cross sections and resonance shielding factors) in the "Russian" format. Interpolation schemes are used to compute shielding factors applicable to specific compositions. A flux iteration option for computing the elastic removal cross section is also included. Collapsed group cross sections by reactor zone are calculated using flux-weighting. The eigenvalue and spatial flux profiles are computed using standard source-iteration techniques. Convergence is accelerated using fission source over-relaxation. Adjoint calculations are performed by transposing the scattering matrix and fission source and then inverting the group order of the input data. 1DX will also accept input cross sections in the DTF format (i.e., resonance shielded cross sections).

6. RESTRICTIONS OR LIMITATIONS

1DX uses variable dimensioning to make maximum use of existing core storage. All subscripted variables are stored in one array dimensioned to 35,000 on the UNIVAC 1108. Allocation is dynamic on the IBM 360/370.

7. TYPICAL RUNNING TIME

A representative 26-group problem with 30 spatial intervals using data in the Russian format requires about 50 seconds on a UNIVAC 1108 computer. If the cross section data is already in the DTF format, the same problem would require about 5 seconds.

The sample problem requires 12 seconds of CPU time on an IBM 370/195 computer.

8. COMPUTER HARDWARE REQUIREMENTS

1DX is operable on the IBM 360/370 computers or on the UNIVAC 1108 computers. 65 K memory and 7 peripheral storage devices are required on the UNIVAC 1108; 145 K memory and a maximum of 8 storage devices are required on the IBM 360/370 computers.

9. COMPUTER SOFTWARE REQUIREMENTS

Fortran IV and Assembler Language compilers are required.

10. REFERENCE

R. W. Hardie and W. W. Little, Jr., "1DX, A One-Dimensional Diffusion Code for Generating Effective Nuclear Cross Sections," BNWL-954 (March 1969).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and sample problem input and output.

12. DATE OF ABSTRACT

March 1984.